I want to create a simple seismometer based on MMA7361 accelerometer. I read from many literature about seismic wave frequency and peak ground acceleration (PGA). It is clear that MMA7361 qualified for acceleration measuring range 1.5 g or 6 g (maximum earthquake acceleration recorded in history is about 1,24 g). But, it is not defined (on datasheet) about frequency response of this sensor. Seismic wave frequency range (non exploration) can be smaller than 0.001 Hz and maximum frequency up to 200 Hz.

Did you not see in the datsheet (http://www.sparkfun.com/datasheets/Components/General/MMA7361L.pdf) where is says:

Bandwidth ResponseXY Typically 400 HzZ Typically 300 Hz

Since the sensitivity and zero offset will vary with temperature you might want to have your accelerometer in a temperature-controlled environment. The operating temperature range goes up to 85°C so a little oven to keep the temperature around 40°C might do the trick.

Did you not see in the datsheet (http://www.sparkfun.com/datasheets/Components/General/MMA7361L.pdf) where is says:

Bandwidth ResponseXY Typically 400 HzZ Typically 300 Hz

Since the sensitivity and zero offset will vary with temperature you might want to have your accelerometer in a temperature-controlled environment. The operating temperature range goes up to 85°C so a little oven to keep the temperature around 40°C might do the trick.